Boyal Microscopical Society. 
99 
wliich it has received during the past year from our Transatlantic 
neighbours; amongst these may be mentioned the paper of Dr. 
H. D. Schmidt, of New Orleans, on the construction of the dark 
or double-bordered nerve-fibre, and the deductions in a second paper 
by the same author from the observations described in the former. 
We are also indebted to the same author for his elaborate re- 
searches on the development of the human embryo, a paper con- 
taining much valuable information. 
In a communication on pigment-particles, by Dr. Kichardson, 
of the Pennsylvania Hospital, it appears to be rather heroic to 
assume that an experienced microscopist can mistake dirt on the 
slide or covering-glass for pigment-particles between these surfaces : 
the simple act of focussing up or down would probably be sufficient 
to determine the locality of the observed object. 
The paper by Dr. Anthony on the suctorial organs of the 
blow-fly is interesting as giving a satisfactory explanation of the 
function of those well-known forked points that appear on the under 
surface of the framework of the suctorial tubes, which, without the 
appendages of soft tissue described by the author, would not be in 
harmony with the universal type of suctorial apparatus ; and have 
always hitherto remained unintelligible to the writer. 
In the same number of the Journal the paper by our esteemed 
Secretary, Mr. Slack, on beaded silica films artificially formed, is 
important for the insight it gives into the formation of the valves of 
diatoms. The well-known markings of some of these are closely 
imitated : and it appears not improbable that each particular form 
of beading may be due to minute differences of density, pressure, or 
molecular electrical state ; — such being the normal conditions of the 
species respectively imitated. 
The contributions by Dr. Braithwaite on bog-mosses are careful 
and elaborate, and well merit the attention of the botanist. 
Nor must it be omitted to mention the further papers of Dr. 
Koyston-Pigott on the optical characters of the microscope, on the 
important points of which time and space forbid an efficient detailed • 
analysis. 
A valuable communication on the development of the teeth in 
the Batrachia and Eeptilia having been recently made to the Eoyal 
Society by Mr. C. S. Tomes, it may not be uninteresting to the 
Fellows of this Society to receive some notice of it. That the 
accounts of the development of the teeth propounded by Arnold and 
Goodsir was not in all respects correct, was suspected many years 
ago by some histologists. Nevertheless, their views have passed 
unchallenged, and are still to be found in most of our text-books. 
The chief features of the process as described by them were (i) the 
occurrence of an open furrow extending all round the jaw, "the 
primitive dental groove ;" (ii) the appearance on the bottom of this 
